Bone is a major component of the human musculoskeletal system. There are two primary types of bone: trabecular bone and cortical bone.
Trabecular or cancellous bone is an interior meshwork of trabeculae (thin struts). Trabecular bone has an elastic modulus in the order of 1 GPa, and a porosity range from 30% to 90%.
Cortical bone is the dense outer shell of bone, which is also known as compact bone. Its porosity ranges from 5% to 30% while with an elastic modulus is about 18 Gpa.
Bone fractures occur when the bone is loaded to failure. Compression fractures are most common in trabecular bone. Bending and torsional fractures are most common in cortical bone. The implantation of a metal or ceramic prosthesis into fractured or diseased regions, subjects the bone to complex stress states. Loosening and subsidence due to failure of the “implant-bone” interface is an important determining factor for the success of a medical treatment. As such, matching of the mechanical properties of the prosthesis to that of the bone is required.
The use of porous surfaces for biological attachment of the implant through ingrowth of the bone greatly improves the fixation of the implanted prosthesis to the bone. However, with the considerable surface area of the porous TiNi material, in contact with body fluids, nickel ion release, from Ni-enriched precipitates present, into these fluids becomes a concern [Assad M., Chernyshov A., et al. J. Biomed+. Mater. V.64B, 2, 2003, pp. 121-129], due primarily to the relative toxicity of nickel and nickel salts.